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Neuroanesthesia - Dr. Christine Fratzola

us414
April 29, 2021

Neuroanesthesia - Dr. Christine Fratzola

April 21 & 28, 2021 Lecture

us414

April 29, 2021
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  1. • Neuroanatomy • Neurophysiology • Monitoring • Cerebral protection •

    Anesthetic management • Common surgical procedures • Common neurological coexisting diseases • ECT
  2. WHAT IS THE MONRO- KELLIE DOCTRINE? What is normal ICP

    range? How much CSF is produced daily? What is the normal volume of CSF in adult?
  3. • Between .6-17% have an incomplete circle of Willis •

    absent vessels are usually in the posterior circulation • This may pose in increased risk of stroke under certain circumstances
  4. • 7 cervical, 12 thoracic, 5lumbar, 5fused sacral, 3-5 fused

    coccygeal vertebrae • About 70 cm long with cervical and lumbar convex, thoracic and sacral concave • In adults cord ends at L1-L2, in infants L3 while the dural sac ends at S2 in adults and S3 in infants
  5. Brain Metabolism • Main substance for energy is glucose (150g/day)

    • Utilizes over 20% of total oxygen metabolism • Neurons consume 75-80% of energy produced in the brain • Cerebral vessels respond by mechanisms involving nitric oxide, prostaglandins, vasoactive peptides, potassium channels, and endothelin
  6. • Describe the relationship between CBF and CMRO2 • What

    is the effect of the different anesthetic agents on CBF and CMRO2? Inhalation agents, narcotics, propofol, etomidate, ketamine, dexmedetomidine, and benzodiazepines?
  7. CBF/CMRO2 • Coupled in the absence of pathology and/or anesthetics

    • CBF changes are directly proportional to PaCO2 • Volatile Anesthetics lead to uncoupling of CBF/CMRO2 • IV Anesthetics decrease CBF and decrease CMRO2 • Benzos decrease CMRO2, little effect on CBF • Succinylcholine – controversial but believed to increase CBF which can increase ICP • Opioids have minimal effects on CMRO2 and no effect on CBF unless rapid infusion
  8. • What are some of the factors that increase blood

    flow and therefore increase CMRO2 because of coupling?
  9. • Stimulation, arousal, and mild hyperthermia elevate metabolism and flow

    • Sedative hypnotic agents and mild hypothermia decrease flow and metabolism • What are some factors that directly effect CBF, not related to metabolism?
  10. • PCO2 has a strong effect on CBF, each 1mm

    Hg change in PCO2 causes a 3% change in blood flow in a linear relationship • As CBF decreases so does CBV and is why hyperventilation is used to help control ICP. • Can you overdo this effect and does it dissipate over time as the CSF pH normalizes?
  11. Treatment of Elevated ICP • Acute treatment includes elevating head

    of the bed, oxygenation and ventilation to maintain PaO2 >100, PaCO2 30-35 • CSF drainage • Mannitol boluses at 0.25-1g/kg • 3% saline as similar effects as mannitol • Hyperventilation – but CBF drops 3-4% for every 1 mmHg decrease in PCO2
  12. • What is the EEG waveform seen in deep anesthesia?

    • What are some indications for EEG monitoring?
  13. • What are the different evoked potentials that we use

    clinically and what are the benefits? • List them from least to most in their sensitivity to anesthetic effects.
  14. • Brainstem Auditory Evoked Potential (BAEP) - for evaluation of

    brainstem lesions or lesions involving the eighth cranial nerve • Somatosensory Evoked Potential (SSEP) - evaluation of the intact sensory pathway from periphery to sensory cortex(dorsal column) • Motor Evoked Potential (MEP) - monitors descending motor pathways from cortex to periphery(anterior cord) • Visual Evoked Potential (VEP) - evaluate visual pathway
  15. • Detection of deterioration of neuronal function, prevent long term

    injury • Identify return or improvement of function • Although these modalities are sensitive and specific in spine surgery, there is a report that states, even with intraop response to decreased signals, it may not reduce rate of new or worsening perioperative neurological deficit(2010 Spine Journal)
  16. • Transcranial doppler-noninvasive monitor of flow through arteries, Circle of

    Willis. It measures flow velocity which directly related to flow only if the diameter of the vessels is constant. Can detect emboli and debris, useful in CEA, bypass procedures, non-neurologic surgeries in TBI patients, detection of vasospasm in the Neuro ICU
  17. • Brain ischemia results from a failure of supply of

    glucose and O2 to support aerobic metabolism, generation of ATP and maintenance of cellular function • The goal is to lower the metabolic rate, less depletion of ATP reserves during ischemia • What is the newer research focused on?
  18. • Limiting the additional damage that occurs during re-perfusion •

    Toxic oxygen species, excitotoxic amino acids, up regulation of nitric oxide synthase, cellular apoptosis • Moving from neuro protection to metabolic suppression
  19. • A 38-year-old man with a history of spinal cord

    transection at the T2 level 3 years ago is scheduled for suprapubic catheter placement. During surgery, he is noted to have an acute rise in blood pressure, to 204/115 mm Hg. Which of the following signs or symptoms is LEAST likely to coincide with this rise in blood pressure? • Headache • Nasal congestion • Skin flushing in lower extremities • Skin flushing in upper extremities
  20. • Which of the following most likely INCREASES cerebral perfusion

    pressure and cerebral oxygenation? • Dopamine • Norepinephrine • Phenylephrine • Vasopressin
  21. • Which of the following characteristics will BEST distinguish between

    whether a patient is in a persistent vegetative state or a coma? • Ability to follow commands • Ability to communicate • Ability to make purposeful movements • Ability to open eyes
  22. Common Procedures • Transphenoidal hypophasectomy • Surgery and endovascular treatment

    for Aneurysm and AVM • Craniotomy for supratentorial lesions • Posterior Fossa surgery • Epilepsy and Awake craniotomy
  23. • Preoperative goals: • assessment and optimization of modifiable factors

    to maximize outcome • Formulate a preoperative plan • Communicate with patient/and or family
  24. • Anesthetic plan: • Agents and monitors are based on

    procedure and co-morbid conditions, invasive monitors pre or post induction • Muscle relaxant choice-is there a place for use of succinylcholine? • Consider patient's airway/ awake cases/ prone/ 180 degree head position/ pre or post op radiologic studies/monitoring
  25. • Succinylcholine is reasonable to use in emergent situations where

    loss of airway (hypoxia, hypocarbia, and aspiration risk) is a greater risk than the increase in ICP associated with succinylcholine. • Use of a defasciculating dose of non-depolarizing muscle relaxant should be administered prior to using succinylcholine • Use of non-depolarizing muscle relaxant is generally recommended in non-emergent cases, making sure that the patient is fully relaxed and adequate hemodynamic conditions have been achieved prior to intubation
  26. • Fluid management: • Isotonic fluids, mannitol, hypertonic 3% saline:

    what to use when • Transfusion therapy-lower limit for HCT 21%? • Glucose management
  27. • Isotonic, non glucose containing fluids should be utilized •

    Colloid has no proven benefit • Mannitol effective for treatment of intracranial HTN • 3% hypertonic saline beneficial for treatment of severe intracranial hypertension (additionally, anti- inflammatory action) • Hyperglycemia worsens brain ischemia, control of hyperglycemia is important.
  28. • There is no exact hematocrit that is recommended. Below

    21% seems to be a number that most agree upon. • With ongoing intraop blood loss, it may be prudent to keep the HCT higher than 21% to maintain proper oxygen delivery to the brain.
  29. • Concerns during emergence and extubation: • Airway edema in

    prone patients • Airway management in difficult airways-transphenoidal, cervical spine • Hemodynamic concerns in cases with brain edema, vascular malformations • Importance of neuro checks • “deep extubation” • Postoperative studies
  30. • General emergence and extubation goals: smooth emergence and extubation

    is key with an awake patient who can easily be evaluated neurologically • Judicious use of narcotics with the most important goal the ability to evaluate the patient neurologically. Common practice is to use IV tylenol as the principle analgesic • Smooth emergence hemodynamically is also important with maintenance of normal BP. In some cases there are specific BP ranges which may be beneficial related to the surgical procedure.
  31. • Awake and oriented after extubation is also crucial in

    patients with difficult airways, as in cervical spine cases with decreased ROM of the neck, and prone patients with airway edema, or the transphenoidal patient with acromegaly with the nose packed and blood in the airway • Deep extubation is the same as smooth awake extubation with a cooperative patient and can be accomplished with +/- lidocaine, small doses of precedex and minimizing long acting narcotics
  32. Pituitary surgery • Transphenoidal approach-small tumors with minimal supra-cellar extension

    • Frontal craniotomy-for large pituitary tumors not accessible from the transphenoidal approach
  33. • General concerns: • Hormonal replacement may be necessary for

    secreting tumors • DI- intraop or more commonly post op may be treated with DDAVP if unresponsive to fluid restriction • Spinal drain used for injection of air or saline incases of supracellar extension or for treatment of patients with CSF leak
  34. • Syndrome of inappropriate ADH secretion • Cerebral salt wasting

    • Diabetes insipidus • Central • Nephrogenic
  35. Vascular malformation Surgery • Seizure or neurologic deficit may be

    presenting symptoms • preoperative embolization- decreases intraoperative bleeding • Regional hyperemia in surrounding vessels post resection can cause vasogenic edema (lack of auto regulation capabilities) • Bleeding-always a risk • Close BP control and smooth extubation are important
  36. Aneurysm surgery • General concerns: • Transmural pressure: pressure difference

    across the aneurysmal sac, sudden increase in MAP or decrease in ICP can cause rupture • Vasospasm: immediate and 5-14 days after rupture • Blood pressure control: avoid spikes (at risk times: laryngoscopy, headapins, incision, and dissection around aneurysm) • Bleeding: arterial bleeding can be devastating with intraop rupture. • Clipping: conditions for clipping may necessitate use of adenosine • Smooth emergence and extubation important • +/- Post operative angiogram to evaluate flow and check for vasospasm
  37. Endovascular tx and code stroke • Pipeline- flow diverting device

    deployed across the aneurysm neck. Blood in the bypassed aneurysm then clots • Coiling- detachable coils fed in to the aneurysm eventually creating coil/ thrombus complex. Difficult accessibility or wide based aneurysms may not be coilable • Sedation vs general in code stroke patients: current belief is local is better than general as long as patient is cooperative enough to withstand the procedure.
  38. • Code stroke guidelines: immediate assessment in 10min of arrival,

    neurologic assessment by stroke team and CT within 25min, interpretation within 45 min, fibrinolytic tx/thrombectomy within 1 hour of arrival/3hours after onset of symptoms, tpa for up to 4.5hours.
  39. Subarachnoid Hemorrhage • Morbidity and mortality following SAH commonly occur

    secondary rebleeding, cerebral ischemia, and hydrocephalus • Rebleeding often occurs within 24-48 hrs • Vasospasm often concern and large cause of post SAH morbidity and mortality
  40. Posterior Fossa Surgery • Major concerns include injury to vital

    circulatory and respiratory brainstem centers as well as cranial nerves
  41. • 58 year old M recently underwent posterior fossa craniotomy

    for tumor resection 5 days ago. Was taken back to OR for drainage of scalp abscess. Pt has been in recovery room for 2 hours and is still somnilent and not following commands. He received 250mcg of Fentanyl intra-op and anesthesia was maintained with nitrous oxide-isoflurane. Currently he withdraws from pain and his pupils are 3mm equal and reactive. TOF is 4/4. Patient was neuro intact prior to the procedure. What's the next best step?
  42. Epilepsy surgery and awake craniotomy • General concerns: • Pathology

    : tumors in the eloquent areas of the brain (primary motor and somatosensory cortex) • monitoring/ECOG-intraoperative EEG • Toleration of procedure: patient selection important • asleep/awake/asleep technique replaced by awake/sedated with precedex and low dose remifentanil • Intraoperative seizure: treated with iced saline and judicious doses of versed or propofol if needed(maintain airway and spontaneous) • Scalp block:nusing .25% bupivicaine • Neurophysiological monitoring to assess motor or speech
  43. • DBS-deep brain stimulator placement for the treatment of Parkinsons

    or other conditions such as essential tremor. • Performed under deep sedation with periods of wakefulness for testing the placement • Electrodes are placed in the sub-thalamic nucleus(STN), during part I and 1-2 weeks later the generator is placed during part 2 • STN is used for Parkinsons, other areas are used for other diseases
  44. • Laser surgery-utilized for tumors that can not be treated

    with open resection • A laser lead is placed in the center of the tumor utilizing MRI and CT guidance and the ablation is performed with direct MRI guidance under general anesthesia • This methodology may not be utilized for larger tumors outside the functional radius of the laser heated area • This procedure may extend the life of patients with inoperable tumors
  45. Anesthesia for TBI • General concerns: • Airway/ oxygenation/ ventilation

    • Other injuries should be considered when plan anesthetic(hypotension and anemia) • ICP-high ICP frequently found in TBI patients • Hypothermia- only true effective method for brain protection • Barbiturate coma utilized for severe ICP if inoperable or in combination with hemicraniectomy
  46. 38 year old M is brought to the ambulance bay

    after a roll over MVA. His BP is 90/60, HR 125 and O2 saturation 97% on 2L NC. He opens his eyes to painful stimulation, is speaking incomprehensible words and withdraws both upper and lower extremities to pain only. What is his GCS?
  47. 49 year old F has had a blunt head trauma

    from her husband. In the ER trauma bay, the patient is giving inappropriate responses to questions being asked. Her eyes open upon verbal command and shows purposeful movement in all extremities to painful stimuli.
  48. Spine surgery • General concerns: • Neurologic function • Monitoring

    • Airway management • BP management • Positioning • Autonomic hyperreflexia • Ischemic optic neuropathy
  49. Coexisting Diseases • Myasthenia Gravis • Myasthenic Syndrome (Lambert Eaton

    syndrome) • Guillain Barre syndrome • Multiple Sclerosis • Alzheimer's Disease • Parkinson Disease
  50. Coexisting Diseases (cont) • Huntington Disease • Amyotrophic Lateral Sclerosis

    • Muscular Dystrophy and Congenital myopathy • Hyperkalemic Periodic Paralysis • Hypokalemic Periodic Paralysis
  51. In which of the following patients is use of succinylcholine

    for induction most acceptable? • A patient with myotonic dystrophy • A patient with muscular dystrophy • A patient with myasthenia gravis • A patient with multiple sclerosis • A patient with T6 spinal cord transection 2 months ago
  52. Causes of Nicotinic AChR Upregulation: (avoid succinylcholine) - Nerve Injuries

    o Stroke o Spinal cord injury o Intracranial lesions leading to upper motor neuron injury - Burns (24 hours up to 1-2 years after burn injury) - Prolonged immobility (greater than 24 hours) - Prolonged exposure to neuromuscular blockers - Myopathies o Duchenne muscular dystrophy - Denervating Disorders o Multiple sclerosis o Guillain-Barré syndrome o Amyotrophic lateral sclerosis
  53. Which of the following should be Avoided in management of

    patient with hypokalemic periodic paralysis? • Low sodium meal • Dextrose-containing intravenous fluids • Postoperative opioid administration • Potassium containing intravenous fluids
  54. Which of the following has NOT been associated with side

    effects or an exacerbation of symptoms in MS patient? • General Anesthesia • Epidural anesthesia • Spinal anesthesia • Succinylcholine
  55. Myasthenia Gravis • Autoantibodies directed against ACh receptors in the

    post synaptic membrane of NMJ • Resistant to succinylcholine • Sensitive to nondepolarizing muscle relaxants • Treatment: cholinesterase inhibitors (pyridostigmine), corticosteroids, immunosuppressants, IVIG and plasmapheresis
  56. Myasthenic Syndrome • AKA Lambert-Eaton Syndrome • Autoantibodies directed against

    presynaptic voltage gated calcium ion channels resulting in decreased release of ACh • Often associated with small cell lung cancer • Sensitive to effects of BOTH depolarizing and nondepolarizing muscle relaxants • Treatment: 3.4-diaminopyridine
  57. Guillain-Barre syndrome • acute inflammatory demyelinating peripheral polyneuropathy secondary to

    an autoimmune response in association with an infectious process • Most common after respiratory or GI illness (campylobacter, Haemophilus, Mycoplasma, EBV) • Succinylcholine should be avoided because of danger of hyperkalemia • Autonomic dysfunction is common involving sympathetic and parasympathic NS • Cardiovascular manifestations can include hypertension, hypotension, brady/tachyarrhythmias
  58. Multiple Sclerosis • autoimmune disease of inflammation, demyelination, and axonal

    damage to the central nervous system • Clinical criteria for diagnosis (age of onset is between 10- 50 years) signs and symptoms of CNS white matter disease, two or more attacks separated by a month or more and involvement of two or more anatomic areas • Do not use succinylcholine. NDNMB's are safe to use but may have varying sensitivity due to baseline limb weakness • Treatments include corticosteroids, Interferon-beta, glatiramer acetate, azathioprine, and low-dose mexthotrexate.
  59. Alzheimer Disease • Progressive neurological disorder which causes the brain

    to atrophy and brain cells to die leading to worsened cognitive dysfunction and dementia • Involves amyloid-B protein; deposition of amyloid plaques, neurofibrillary tangles, and neuronal apoptosis • Treatment includes acetylcholineasterase inhibitors (donepezil, rivastigmine, galantamine) and NMDA inhibitor (Memantine)
  60. Parkinson Disease • Degenerative CNS disease cause by loss of

    dopaminergic cells in basal ganglia • Levodopa used in combination with drugs such as carbidopa (peripheral decarboxylase inhibitor) and entacapone (catechol-o- methyltransferase inhibitor) that prevent adverse peripheral effects of dopamine
  61. Huntington Disease • Autosomal dominant progressive neurodegeneration, trinucleotide repeat disorder

    • Can experience delayed emergence and increased likelihood of resp complications • Decreased plasma cholinesterase activity may prolong response to succinylcholine
  62. Amyotrophic Lateral Sclerosis • AKA Lou Gehrig Disease • Degenerative

    disease of motor neurons, upper and lower • Riluzole a glutamate release inhibitor is only drug approved for ALS • May be sensitive to nondepolarizing muscle relaxants • Can have hyperkalemic response with use of succinylcholine. Spinal anesthesia is usually avoided
  63. Muscular Dystrophy • Characterized by progressive skeletal muscle weakness •

    Pathology involves insufficient or abnormal proteins that form the cytoskeleton of the muscle membrane • Duchenne muscular dystrophy • Becker muscular dystrophy • Emery-Dreifuss muscular dystrophy
  64. Congenital muscular dystrophy and myopathy • Onset of hypotonia during

    infancy, developmental delay, feeding difficulties and respiratory dysfunction • May be susceptible to malignant hyperthermia • Succinylcholine should be avoided and may be sensitive to NDNMB's • Myotonic dystrophy – dysfunction of ion channels in muscle membrane
  65. Hyperkalemic Periodic Paralysis • Autosomal dominant disease that leads to

    intermittent weakness • Sodium ion channel mutation that causes prolonged muscle membrane depolarization and flaccid paralysis • Attacks can be provoked by potassium loading, rest after exercise, stressful situations and cold temperatures • Treatment: glucose, insulin, epinephrine, calcium
  66. Hypokalemic Periodic Paralysis • “channelopathy” caused by defective sodium, calcium

    or potassium ion-channels. cause weakness by partial depolarization of the muscle cells, without generating action potentials. • Triggers: hypothermia, rest after exercise, metabolic alkalosis, carbohydrate loading, meals with high Na content • intraoperatively, monitor potassium levels and avoid glucose solutions or solutions with a high sodium content.
  67. • A 40-year-old female with severe depression is scheduled to

    begin electroconvulsive therapy (ECT). Which of the following is the LEAST likely response to ECT? • Bradycardia • Short term memory loss • Decreased cerebral blood flow • Tachycardia
  68. Electroconvulsive Therapy (ECT) • Utilized for severe depression refractory to

    medication, bipolar disorder, schizophrenia • Generalized epileptic seizure induced by electrical stimulation of the brain • Duration of the seizure is important for the overall therapeutic effect • Contraindications
  69. ECT • Initial tonic phase – parasympathetic stimulation • Followed

    by clonic phase – sympathetic stimulation • Management includes brief general anesthesia and possibly muscle paralysis • Hypercarbia increases seizure threshold and benzodiazepines raise seizure threshold • Bite block***
  70. • The anesthesiologist wishes to optimize intubation conditions for a

    patient who will undergo electroconvulsive therapy (ECT). Which of the following intravenous drugs would be the LEAST appropriate for this patient, given the type of procedure being performed? • Etomidate • Glycopyrrolate • Lidocaine • Remifentanil
  71. References • Barash, Paul G., Bruce F. Cullen, Robert K.

    Stoelting, Michael K. Cahalan, M. Christine Stock, Rafael Ortega, Sam R. Sharar, and Natalie F. Holt. Clinical Anesthesia. Wolters Kluwer. 8th ed. 2017. • Butterworth, John F., David C. Mackey, and John D. Wasnick. Morgan & Mikhail's Clinical Anesthesiology. McGraw-Hill. 6th ed. 2018. • Miller, Ronald D. and Manuel C. Pardo, Jr. Basics of Anesthesia. Elsevier. 6th ed. 2011. • OpenAnesthesia.org. IARS. 2021. • Trentman, Terrence L., Brantley D. Gaitan, Bhargavi Gali, Rebecca L. Johnson, Jeffrey T. Mueller, Steven H. Rose, and Toby N. Weingarten. Faust's Anesthesiology Review. Elsevier. 5th Ed. 2020.